The present invention relates to a data converter for receiving data sent from outside, replacing a part of the received data, and outputting the data.
The ISDB-T (Integrated Services Digital Broadcasting, Terrestrial) which started on December 2003 in Japan is unlike conventional terrestrial digital broadcasting and can broadcast not only video and audio but also community-based data. However, even when executing community-based data broadcasting, data must be updated by each broadcasting station; accordingly, the community-based data broadcasting is limited to the broadcasting of data varied in units of prefectural broadcasting.
On the contrary, there is proposed area-broadcasting similar to a conventional small-scale FM station in which corresponding prefectural broadcasting units are further segmented. This broadcasting system uses the same frequency as used for the prefectural-based data broadcasting and broadcasts the same video and audio contents as broadcasted in units of prefectural broadcasting. Furthermore, this broadcasting system can send out data broadcasting unique to a specific narrow area, namely, for example, a shielded environment such as underground mall and an amusement facility, and which enables users to receive data via data broadcasting and display contents of the received data only in the corresponding area.
In general, in many cases as to the broadcasting limited to a specific area, information is delivered via a communication system such as a multicast-system communication medium using the Internet, rather than using a broadcasting system. However, in an information delivery system that uses a communication medium like a multicast system, if important information, such as disaster information including information about earthquakes expected to occur in Japan or emergency information, is broadcasted to receivers and many of the receivers access the delivery source of information in a short period of time, the occurrence of congestion is inevitable, causing communication failure; consequently, there is a high possibility that necessary information is not delivered to all of the receivers. Therefore, in order to make area-broadcasting continuously available in case of the occurrence of emergency information or disaster information, it is obvious that the area-broadcasting should be achieved by using a broadcasting medium rather than using a communication medium.
Specifically, in the ISDB-T terrestrial digital broadcasting system, it is possible to use one-segment terrestrial digital broadcasting which enables mobiles to receive broadcasting; therefore, it is possible to send information to many users in the broadcasting area. The subject is how to send out data broadcasting unique to the above-mentioned shielded environment or amusement facility by using the broadcasting system within a framework of terrestrial digital broadcasting.
In order to broadcast the same video and audio as that broadcasted by a prefectural broadcasting station and broadcast data unique to a specific narrow area such as the above-mentioned shielded environment or amusement facility, from the viewpoint of the effective use of the broadcasting data band, it is necessary to provide a relay station for each specific narrow area as an area-broadcasting target; wherein each relay station is used to replace prefectural broadcasting data contents with local broadcasting data contents and send out data broadcasting of the replaced contents. To achieve this broadcasting, it is necessary to provide a broadcasting data converter for replacing the data broadcasting contents in each relay station.
With regard to an apparatus which replaces data broadcasting contents in a relay station, a technology has been disclosed in Japanese Patent Laid-open No. 2004-135315 and the Journal of technical disclosure WO02/082699.
Among those, a system described in Japanese Patent Laid-open No. 2004-135315 is configured to output data replacing a part of the data while keeping a data input speed and a data output speed identical. According to this system, data transmission speed can be kept constant between a data broadcasting program broadcasted by a key station and a data broadcasting program broadcasted by a local station. Accordingly, even any local area can do data broadcasting with a frequency band equivalent to that of a key station, thereby making it possible to change contents of the data broadcasting program according to the regional characteristics without changing the frequency band.
Furthermore, Internal publication No. WO02/082699 discloses the following data broadcasting program stream transmission system. The system produces a data broadcasting program stream in which contents including a plurality of commercial messages and event messages corresponding to each commercial message are repeatedly multiplexed. When a receiver is received the data broadcasting program stream, it separates constituent elements of the data broadcasting program from the contents, and determines whether to include each constituent element in the contents. When determining that a commercial message should be included in the contents, a message for controlling the commercial message processing timing is included together with the commercial message; or when determining that a certain commercial message should be not included, the data broadcasting program stream which repeatedly multiplexes the contents not including the event message corresponding to commercial message is outputted. Furthermore, the system discloses the following data broadcasting program stream transmission unit. That is, when a data broadcasting program multiplexed with a transport stream is broadcasted together with a digital broadcasting program, the apparatus uses a first data broadcasting program transport stream distributed over the Internet by another broadcasting station. Thereby, it is possible for a receiving unit to control the commercial message processing timing by receiving the message.
Furthermore, Japanese Patent Laid-open No. 2001-045371 discloses a television picture switching method for detecting the boundaries of a plurality of continuously transmitted TV broadcasting materials by detecting a replacement frame and replacing a plurality of TV broadcasting materials.